In recent years, as a core material of a seat cushion for a vehicle, a core material of a seat cushion for a vehicle in which a reinforcing member made of metal and the like is buried in and integrated into a thermoplastic resin expanded beads molded article (hereinafter sometimes simply referred to as “expanded beads molded article”) is used. In this case, the reinforcing member buried in the expanded beads molded article functions as a structural frame for attaching to a vehicle body, a structural frame for seat arrangement, a reinforcing material during collision, and the like.
As a member formed by integrating an expanded beads molded article and a reinforcing member, a composite expanded beads molded article composed of a base foam resin layer and the reinforcing member disposed inside the base foam resin layer has been proposed, in which a foam layer of a foamable resin covering the reinforcing member is engaged or fused with the base foam resin layer (see, for example, Patent Literature 1).
Such a composite expanded beads molded article is manufactured, for example, by so-called insert molding, in which a reinforcing member is disposed at a predetermined position in a mold, and then the expanded beads constituting the base is filled in the mold, heated, and fused.